Special Issue "Workplans II: Workshop for Planetary Nebula Observations"

A special issue of Galaxies (ISSN 2075-4434).

Deadline for manuscript submissions: 30 October 2020.

Special Issue Editor

Dr. Toshiya Ueta
Website
Guest Editor
Department of Physics and Astronomy, University of Denver, Denver, CO 80208, United States
Interests: stellar evolution; mass loss; circumstellar matter

Special Issue Information

Dear Colleagues,

This workshop will be the second of the WORKPLANS workshop series we started back in 2016 at the Lorentz Center (WORKPLANS 2016: http://www.lorentzcenter.nl/lc/web/2016/786/info.php3?wsid=786&venue=Oort).

The main goal of this workshop series is to build up a network of planetary nebulae (PNe) experts to address the main open questions in the field of planetary nebulae research. The specific aims of this workshop are (i) to discuss the most relevant topics to be investigated by the community in the following years, (ii) to set up an excellent network of researchers with complementary expertise to write high-level observing proposals for the most modern telescopes available at present (ALMA, Chandra, SOFIA, VLT, GTC, HST, etc.) to address those topics, and (iii) to develop strategies for future observatories (JWST, ELT, etc.). We plan to achieve these goals by bringing together experts in several sub-areas of the PNe research field, namely, the analysis and interpretation of PNe observational data, the theoretical modeling of gas and dust emission, the evolution from AGB stars (PNe progenitors) to PNe, and the instrumentation and technical characteristics of the relevant observatories. During the workshop, we will discuss and prepare multiwavelength observational proposals using the current and next-generation state-of-the art facilities.

The International Astronomical Union (IAU) Planetary Nebula Working Group discusses several open questions in the White Paper entitled “The present and future of planetary nebula research” (Kwitter et al. 2014, RMxAA, 50, 203). According to the paper, the main problems to be investigated by the community in the next few years are:

  • Uncovering PNe that cannot be identified in the optical spectral range;
  • Improving central star evolutionary models;
  • Improving our knowledge of the atmospheres and winds of central stars;
  • Investigating the role of binary central stars in the evolution/formation of PNe;
  • Understanding the history and mechanisms of mass-loss and structure formation in the circumstellar nebulae;
  • Improving the techniques to derive chemical abundances;
  • Understanding the abundance discrepancies measured from collisional and recombination lines; and
  • Understanding the formation mechanisms and survival of dust and molecules in PNe.

Solving such issues would have a great impact not only for the PN research community, but also for the astronomical community as a whole—PNe are unique astrophysical laboratories in which we can investigate a wide variety of physical conditions, from highly-ionized plasma to low-temperature dusty molecular regions in a spatially-resolved manner, and their findings are applicable not only to PNe but also other astrophysical objects with similar characteristics. PNe are also an important source of material (dust and gas) for the interstellar medium.

Kwitter et al. (2014) also clarified the need of further multiwavelength observations in the PN research field and serve as a motivation for this workshop series. As in any topic in Astronomy, research on PNe is widely driven by observations. New facilities built in recent decades have improved the instruments and opened new spectral windows. Future telescopes, such as the James Webb Space Telescope (JWST), will play a key role in the state-of-art astronomy research in the next few years. Multiwavelength studies have become possible and, since different wavelength ranges probe different realms of chemistry and physics, they have already greatly improved our understanding in a wide range of astronomical objects, including PNe. This is a strong motivation for bringing together researchers with expertise in different wavelength ranges with a common goal: to understand the formation and evolution of PNe.

To fully explore the possibilities of the current and future instruments for the study of PNe, it is essential to aggregate different expertise, and the formation of an international network of scientists is then a natural step. Such a network provides a framework for a more efficient use of astronomical data and helps to compete for time on the main telescopes, where strong worldwide dispute is an important factor.

Dr. Toshiya Ueta
Guest Editor

Manuscript Submission Information

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Keywords

  • stars: evolution
  • stars: late type
  • stars: mass-loss
  • stars: winds and outflows
  • planetary nebulae
  • plasmas
  • stars: abundances
  • dust
  • extinction
  • astrochemistry

Published Papers (18 papers)

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Editorial

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Open AccessEditorial
WORKPLANS: Workshop on Planetary Nebula Observations
Galaxies 2020, 8(1), 23; https://doi.org/10.3390/galaxies8010023 - 16 Mar 2020
Cited by 1
Abstract
This workshop is the second of the WORKPLANS series, which we started in 2016. The main goal of WORKPLANS is to build up a network of planetary nebulae (PNe) experts to address the main open questions in the field of PNe research. The [...] Read more.
This workshop is the second of the WORKPLANS series, which we started in 2016. The main goal of WORKPLANS is to build up a network of planetary nebulae (PNe) experts to address the main open questions in the field of PNe research. The specific aims of the WORKPLANS workshop series are (i) to discuss and prioritize the most important topics to be investigated by the PN community in the following years; (ii) to establish a network of excellent researchers with complementary expertise; (iii) to formulate ambitious observing proposals for the most advanced telescopes and instrumentation presently available (ALMA, SOFIA, VLT, GTC, HST, etc.), addressing those topics; and (iv) to develop strategies for major proposals to future observatories (JWST, ELT, SPICA, Athena, etc.). To achieve these goals, WORKPLANS II brought together experts in all key sub-areas of the PNe research field, namely: analysis and interpretation of PNe observational data; theoretical modeling of gas and dust emission; evolution from Asymptotic Giant Branch stars (PNe progenitors) to PNe; and the instrumentation and technical characteristics of the relevant observatories. Full article
(This article belongs to the Special Issue Workplans II: Workshop for Planetary Nebula Observations)
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Research

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Open AccessArticle
Observing Planetary and Pre-Planetary Nebulae with the James Webb Space Telescope
Galaxies 2020, 8(3), 61; https://doi.org/10.3390/galaxies8030061 - 12 Aug 2020
Abstract
Most stars in the Universe that leave the main sequence in a Hubble time will end their lives evolving through the Planetary Nebula (PN) evolutionary phase. The heavy mass loss which occurs during the preceding Asymptotic Giant Branch (AGB) phase is important across [...] Read more.
Most stars in the Universe that leave the main sequence in a Hubble time will end their lives evolving through the Planetary Nebula (PN) evolutionary phase. The heavy mass loss which occurs during the preceding Asymptotic Giant Branch (AGB) phase is important across astrophysics, dramatically changing the course of stellar evolution, contributing to the dust content of the interstellar medium, and influencing its chemical composition. The evolution from the AGB phase to the PN phases remains poorly understood, especially the dramatic transformation that occurs in the morphology of the mass-ejecta as AGB stars enter the post-AGB phase and their round circumstellar envelopes evolve into pre-PNe (PPNe) and then to PNe. The majority of PPNe and PNe deviate strongly from spherical symmetry. Strong binary interactions most likely play a fundamental role in influencing this evolutionary phase, but the details of these interactions remain shrouded in mystery. Thus, understanding the formation and evolution of these objects is of wide astrophysical importance. PNe have long been known to emit across a very large span of wavelengths, from the radio to X-rays. Extensive use of space-based observatories at X-ray (Chandra/ XMM-Newton), optical (HST) and mid- to far-infrared (Spitzer, Herschel) wavelengths in recent years has produced significant new advances in our knowledge of these objects. Given the expected advent of the James Webb Space Telescope (JWST) in the near future, we focus on future high-angular-resolution, high-sensitivity observations at near and mid-IR wavelengths with JWST that can help in addressing the major unsolved problems in the study of PNe and their progenitors. Full article
(This article belongs to the Special Issue Workplans II: Workshop for Planetary Nebula Observations)
Open AccessArticle
First Results from a Panchromatic HST/WFC3 Imaging Study of the Young, Rapidly Evolving Planetary Nebulae NGC 7027 and NGC 6302
Galaxies 2020, 8(2), 49; https://doi.org/10.3390/galaxies8020049 - 15 Jun 2020
Abstract
We present the first results from comprehensive, near-UV-to-near-IR Hubble Space Telescope Wide Field Camera 3 (WFC3) emission-line imaging studies of two young planetary nebulae (PNe), NGC 7027 and NGC 6302. These two objects represent key sources for purposes of understanding PNe shaping processes. [...] Read more.
We present the first results from comprehensive, near-UV-to-near-IR Hubble Space Telescope Wide Field Camera 3 (WFC3) emission-line imaging studies of two young planetary nebulae (PNe), NGC 7027 and NGC 6302. These two objects represent key sources for purposes of understanding PNe shaping processes. Both nebulae feature axisymmetric and point-symmetric (bipolar) structures and, despite hot central stars and high nebular excitation states, both harbor large masses of molecular gas and dust. The sweeping wavelength coverage of our Cycle 27 Hubble Space Telescope (HST)/WFC3 imaging surveys targeting these two rapidly evolving PNe will provide a battery of essential tests for theories describing the structural and chemical evolution of evolved star ejecta. Here, we present initial color overlays for selected images, and we highlight some of the first results gleaned from the surveys. Full article
(This article belongs to the Special Issue Workplans II: Workshop for Planetary Nebula Observations)
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Open AccessArticle
The Web of Micro-Structures in IC 4593
Galaxies 2020, 8(2), 46; https://doi.org/10.3390/galaxies8020046 - 30 May 2020
Abstract
In addition to large-scale structures, planetary nebulae (PNe) show small-scale structures that emit mainly in low-ionization species such as [N ii], [S ii], [O ii], and [O i], known as LISs. Here, we present the analysis of optical long-slit [...] Read more.
In addition to large-scale structures, planetary nebulae (PNe) show small-scale structures that emit mainly in low-ionization species such as [N ii], [S ii], [O ii], and [O i], known as LISs. Here, we present the analysis of optical long-slit spectra, for three slit positions, of the PN IC 4593, which possesses a pair of knots and an isolated low-ionization knot. The motivation for this work is the need to characterize LISs completely to evaluate their impact on the PNe studies. These data allow us to derive the physical properties and ionization state for each morphological component of the nebula, including its pair of knots and individual knot. Due to the large uncertainties in the [S ii] derived electron densities, we cannot confirm any contrast between the LISs’ electron densities and the surrounding nebula, found in numerous other LISs. Though the lack of spatially-resolved physical parameters in the literature prevents further comparisons, in general, our results derived for the entire nebula agree with previous studies. Full article
(This article belongs to the Special Issue Workplans II: Workshop for Planetary Nebula Observations)
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Open AccessArticle
Shaping of Planetary Nebulae by Exoplanets
Galaxies 2020, 8(2), 41; https://doi.org/10.3390/galaxies8020041 - 14 May 2020
Abstract
(1) Background: We investigate the hypothesis that exoplanet engulfment can help explain the observed non-spherical planetary nebula population, as a complementary shaping mechanism to the binary hypothesis. The aim is to investigate the extent to which massive planets can explain the population of [...] Read more.
(1) Background: We investigate the hypothesis that exoplanet engulfment can help explain the observed non-spherical planetary nebula population, as a complementary shaping mechanism to the binary hypothesis. The aim is to investigate the extent to which massive planets can explain the population of non-spherical planetary nebulae; (2) Methods: This research utilises a new tool to calculate the planet-fraction of planetary nebulae progenitor stars called simsplash; (3) Results: we conclude that ∼15–30% of non-spherical planetary nebulae around single stars will have a history in which they engulfed a massive planet on the AGB; and (4) Conclusions: Engulfment of massive exoplanets may contribute significantly to the formation of non-spherical planetary nebulae around single stars, yet appears to be insufficient to explain them all. Full article
(This article belongs to the Special Issue Workplans II: Workshop for Planetary Nebula Observations)
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Open AccessArticle
The Interaction of Type Ia Supernovae with Planetary Nebulae: The Case of Kepler’s Supernova Remnant
Galaxies 2020, 8(2), 38; https://doi.org/10.3390/galaxies8020038 - 04 May 2020
Abstract
One of the key methods for determining the unknown nature of Type Ia supernovae (SNe Ia) is the search for traces of interaction between the SN ejecta and the circumstellar structures at the resulting supernova remnants (SNRs Ia). So far, the observables that [...] Read more.
One of the key methods for determining the unknown nature of Type Ia supernovae (SNe Ia) is the search for traces of interaction between the SN ejecta and the circumstellar structures at the resulting supernova remnants (SNRs Ia). So far, the observables that we receive from well-studied SNRs Ia cannot be explained self-consistently by any model presented in the literature. In this study, we suggest that the circumstellar medium (CSM) being observed to surround several SNRs Ia was mainly shaped by planetary nebulae (PNe) that originated from one or both progenitor stars. Performing two-dimensional hydrodynamic simulations, we show that the ambient medium shaped by PNe can account for several properties of the CSM that have been found to surround SNe Ia and their remnants. Finally, we model Kepler’s SNR considering that the SN explosion occurred inside a bipolar PN. Our simulations show good agreement with the observed morphological and kinematic properties of Kepler’s SNR. In particular, our model reproduces the current expansion parameter of Kepler’s SNR, the partial interaction of the remnant with a dense CSM at its northern region and finally the existence of two opposite protrusions (‘ears’) at the equatorial plane of the SNR. Full article
(This article belongs to the Special Issue Workplans II: Workshop for Planetary Nebula Observations)
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Open AccessArticle
A Preferred Orientation Angle for Bipolar Planetary Nebulae
Galaxies 2020, 8(2), 34; https://doi.org/10.3390/galaxies8020034 - 20 Apr 2020
Abstract
We present preliminary results from measuring Galactic orientation angles of 766 elliptical and bipolar Planetary Nebulae (PNe) in the Hong Kong/Australian Astronomical Observatory/Strasbourg Observatory H-alpha Planetary Nebula research platform and database (HASH DB). For elliptical PNe the distribution of orientation angles is found [...] Read more.
We present preliminary results from measuring Galactic orientation angles of 766 elliptical and bipolar Planetary Nebulae (PNe) in the Hong Kong/Australian Astronomical Observatory/Strasbourg Observatory H-alpha Planetary Nebula research platform and database (HASH DB). For elliptical PNe the distribution of orientation angles is found to be more or less uniform. However, for bipolar PNe there is statistically significant evidence for preferred orientation angles (as tentatively reported before with smaller samples) across the whole Galaxy. Full article
(This article belongs to the Special Issue Workplans II: Workshop for Planetary Nebula Observations)
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Open AccessArticle
Irradiation Investigation: Exploring the Molecular Gas in NGC 7293
Galaxies 2020, 8(2), 32; https://doi.org/10.3390/galaxies8020032 - 08 Apr 2020
Abstract
Background: Many planetary nebulae retain significant quantities of molecular gas and dust despite their signature hostile radiation environments and energetic shocks. Photoionization and dissociation by extreme UV and (often) X-ray emission from their central stars drive the chemical processing of this material. Their [...] Read more.
Background: Many planetary nebulae retain significant quantities of molecular gas and dust despite their signature hostile radiation environments and energetic shocks. Photoionization and dissociation by extreme UV and (often) X-ray emission from their central stars drive the chemical processing of this material. Their well-defined geometries make planetary nebulae ideal testbeds for modeling the effects of radiation-driven heating and chemistry on molecular gas in photodissociation regions. Methods: We have carried out IRAM 30m/APEX 12m/ALMA radio studies of the Helix Nebula and its molecule-rich globules, exploiting the unique properties of the Helix to follow up our discovery of an anti-correlation between HNC/HCN line intensity ratio and central star UV Luminosity. Results: Analysis of HNC/HCN across the Helix Nebula reveals the line ratio increases with distance from the central star, and thus decreasing incident UV flux, indicative of the utility of the HNC/HCN ratio as a tracer of UV irradiation in photodissociation environments. However, modeling of the observed regions suggests HNC/HCN should decrease with greater distance, contrary to the observed trend. Conclusion: HNC/HCN acts as an effective tracer of UV irradiation of cold molecular gas. Further model studies are required. Full article
(This article belongs to the Special Issue Workplans II: Workshop for Planetary Nebula Observations)
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Open AccessArticle
Integral Field Spectroscopy of Planetary Nebulae with MUSE
Galaxies 2020, 8(2), 31; https://doi.org/10.3390/galaxies8020031 - 03 Apr 2020
Abstract
The Multi-Unit Spectroscopic Explorer (MUSE) is a large integral field unit mounted on the ESO Very Large Telescope. Its spatial (60 arcsecond field) and wavelength (4800–9300Å) coverage is well suited to detailed imaging spectroscopy of extended planetary nebulae, such as in the Galaxy. [...] Read more.
The Multi-Unit Spectroscopic Explorer (MUSE) is a large integral field unit mounted on the ESO Very Large Telescope. Its spatial (60 arcsecond field) and wavelength (4800–9300Å) coverage is well suited to detailed imaging spectroscopy of extended planetary nebulae, such as in the Galaxy. An overview of the capabilities of MUSE applied to Planetary Nebulae (PNe) is provided together with the specific advantages and disadvantages. Some examples of archival MUSE observations of PNe are provided. MUSE datacubes for two targets (NGC 3132 and NGC 7009) are analyzed in detail, and they are used to show the advances achievable for planetary nebula studies. Prospects for further MUSE observations of PNe and a broader analysis of existing datasets are outlined. Full article
(This article belongs to the Special Issue Workplans II: Workshop for Planetary Nebula Observations)
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Open AccessArticle
Molecular Hydrogen Microstructures in Planetary Nebulae
Galaxies 2020, 8(2), 30; https://doi.org/10.3390/galaxies8020030 - 01 Apr 2020
Cited by 1
Abstract
Molecular hydrogen (H 2 ) emission is commonly detected in planetary nebulae (PNe), specially in objects with bipolar morphologies. New studies showed that H 2 gas is also packed in microstructures embedded in PNe of any morphological type. Despite the presence of H [...] Read more.
Molecular hydrogen (H 2 ) emission is commonly detected in planetary nebulae (PNe), specially in objects with bipolar morphologies. New studies showed that H 2 gas is also packed in microstructures embedded in PNe of any morphological type. Despite the presence of H 2 in cometary knots being known for years, only in the last five years, much deeper imagery of PNe have revealed that H 2 also exists in other types of low-ionisation microstructures (LISs). Significant differences are found between the host PNe of cometary knots and other types of LISs, such as nebula age, central star temperature (evolutionary stage) and the absolute sizes of the microstructure itself. Full article
(This article belongs to the Special Issue Workplans II: Workshop for Planetary Nebula Observations)
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Open AccessArticle
Gaia DR2 Distances to Planetary Nebulae
Galaxies 2020, 8(2), 29; https://doi.org/10.3390/galaxies8020029 - 01 Apr 2020
Cited by 2
Abstract
The aim of this work is to examine distances to planetary nebulae (PNe) together with other properties that were derived from them, using the astrometry of Gaia Data Release 2 (DR2). We were able to identify 1571 objects classified as PNe, for which [...] Read more.
The aim of this work is to examine distances to planetary nebulae (PNe) together with other properties that were derived from them, using the astrometry of Gaia Data Release 2 (DR2). We were able to identify 1571 objects classified as PNe, for which we assumed distances calculated following a Bayesian statistical approach. From those objects, we selected a sample of PNe with good quality parallax measurements and distance derivations, which we called Golden Astrometry PNe sample (GAPN). In this paper we will review the physical properties of the stars and nebulae in this subsample of PNe. Full article
(This article belongs to the Special Issue Workplans II: Workshop for Planetary Nebula Observations)
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Open AccessArticle
Shaping Planetary Nebulae with Jets and the Grazing Envelope Evolution
Galaxies 2020, 8(1), 26; https://doi.org/10.3390/galaxies8010026 - 18 Mar 2020
Cited by 4
Abstract
I argue that the high percentage of planetary nebulae (PNe) that are shaped by jets show that main sequence stars in binary systems can accrete mass at a high rate from an accretion disk and launch jets. Not only does this allow jets [...] Read more.
I argue that the high percentage of planetary nebulae (PNe) that are shaped by jets show that main sequence stars in binary systems can accrete mass at a high rate from an accretion disk and launch jets. Not only does this allow jets to shape PNe, but this also points to the importance of jets in other types of binary systems and in other processes. These processes include the grazing envelope evolution (GEE), the common envelope evolution (CEE), and the efficient conversion of kinetic energy to radiation in outflows. Additionally, the jets point to the possibility that many systems launch jets as they enter the CEE, possibly through a GEE phase. The other binary systems in which jets might play significant roles include intermediate-luminosity optical transients (ILOTs), supernova impostors (including pre-explosion outbursts), post-CEE binary systems, post-GEE binary systems, and progenitors of neutron star binary systems and black hole binary systems. One of the immediate consequences is that the outflow of these systems is highly-non-spherical, including bipolar lobes, jets, and rings. Full article
(This article belongs to the Special Issue Workplans II: Workshop for Planetary Nebula Observations)
Open AccessArticle
X-ray Observations of Planetary Nebulae since WORKPLANS I and Beyond
Galaxies 2020, 8(1), 24; https://doi.org/10.3390/galaxies8010024 - 17 Mar 2020
Cited by 1
Abstract
Planetary nebulae (PNe) were expected to be filled with hot pressurized gas driving their expansion. ROSAT hinted at the presence of diffuse X-ray emission from these hot bubbles and detected the first sources of hard X-ray emission from their central stars, but it [...] Read more.
Planetary nebulae (PNe) were expected to be filled with hot pressurized gas driving their expansion. ROSAT hinted at the presence of diffuse X-ray emission from these hot bubbles and detected the first sources of hard X-ray emission from their central stars, but it was not until the advent of Chandra and XMM-Newton that we became able to study in detail their occurrence and physical properties. Here I review the progress in the X-ray observations of PNe since the first WORKshop for PLAnetary Nebulae observationS (WORKPLANS) and present the perspective for future X-ray missions with particular emphasis on eROSITA. Full article
(This article belongs to the Special Issue Workplans II: Workshop for Planetary Nebula Observations)
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Review

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Open AccessReview
Neutron-Capture Element Abundances in Planetary Nebulae
Galaxies 2020, 8(2), 50; https://doi.org/10.3390/galaxies8020050 - 17 Jun 2020
Abstract
Nebular spectroscopy is a valuable tool for assessing the production of heavy elements by slow neutron(n)-capture nucleosynthesis (the s-process). Several transitions of n-capture elements have been identified in planetary nebulae (PNe) in the last few years, with the aid [...] Read more.
Nebular spectroscopy is a valuable tool for assessing the production of heavy elements by slow neutron(n)-capture nucleosynthesis (the s-process). Several transitions of n-capture elements have been identified in planetary nebulae (PNe) in the last few years, with the aid of sensitive, high-resolution, near-infrared spectrometers. Combined with optical spectroscopy, the newly discovered near-infrared lines enable more accurate abundance determinations than previously possible, and provide access to elements that had not previously been studied in PNe or their progenitors. Neutron-capture elements have also been detected in PNe in the Sagittarius Dwarf galaxy and in the Magellanic Clouds. In this brief review, I discuss developments in observational studies of s-process enrichments in PNe, with an emphasis on the last five years, and note some open questions and preliminary trends. Full article
(This article belongs to the Special Issue Workplans II: Workshop for Planetary Nebula Observations)
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Open AccessFeature PaperReview
Infrared Observations of Planetary Nebulae and Related Objects
Galaxies 2020, 8(2), 44; https://doi.org/10.3390/galaxies8020044 - 18 May 2020
Abstract
In this paper, I present how near and mid-infrared observations can be used for the study of planetary nebulae and related objects. I present the main observing techniques, from the ground and space, highlighting main differences and how they can be complementary. I [...] Read more.
In this paper, I present how near and mid-infrared observations can be used for the study of planetary nebulae and related objects. I present the main observing techniques, from the ground and space, highlighting main differences and how they can be complementary. I also highlight some new observing facilities and present the infrared observatories of the future to show that the future of infrared observations of planetary nebulae is bright. Full article
(This article belongs to the Special Issue Workplans II: Workshop for Planetary Nebula Observations)
Open AccessReview
Binary Central Stars of Planetary Nebulae
Galaxies 2020, 8(2), 28; https://doi.org/10.3390/galaxies8020028 - 01 Apr 2020
Cited by 1
Abstract
It is now clear that a vast majority of intermediate-mass stars have stellar and/or sub-stellar companions, therefore it is no longer appropriate to consider planetary nebulae as a single-star phenomenon, although some single, isolated stars may well lead to planetary nebulae. As such, [...] Read more.
It is now clear that a vast majority of intermediate-mass stars have stellar and/or sub-stellar companions, therefore it is no longer appropriate to consider planetary nebulae as a single-star phenomenon, although some single, isolated stars may well lead to planetary nebulae. As such, while understanding binary evolution is critical for furthering our knowledge of planetary nebulae, the converse is also true: planetary nebulae can be valuable tools with which to probe binary evolution. In this brief review, I attempt to summarise some of our current understanding with regards to the role of binarity in the formation of planetary nebulae, and the areas in which continued study of planetary nebulae may have wider ramifications for our grasp on the fundaments of binary evolution. Full article
(This article belongs to the Special Issue Workplans II: Workshop for Planetary Nebula Observations)
Open AccessReview
(Sub)mm-Wavelength Observations of Pre-Planetary Nebulae and Young Planetary Nebulae
Galaxies 2020, 8(1), 21; https://doi.org/10.3390/galaxies8010021 - 10 Mar 2020
Abstract
This is a non-comprehensive review of observations of pre-Planetary Nebulae (pPNe) and young Planetary Nebulae (yPNe) at (sub)mm-wavelengths, a valuable window for probing multi-phased gas and dust in these objects. This contribution focuses on observations of molecular lines (from carbon monoxide—CO—and other species), [...] Read more.
This is a non-comprehensive review of observations of pre-Planetary Nebulae (pPNe) and young Planetary Nebulae (yPNe) at (sub)mm-wavelengths, a valuable window for probing multi-phased gas and dust in these objects. This contribution focuses on observations of molecular lines (from carbon monoxide—CO—and other species), and briefly at the end, on hydrogen radio recombination lines from the emerging H ii regions at the center of yPNe. The main goal of this contribution is to show the potential of (sub)mm-wavelength observations of pPNe/yPNe to help the community to devise and develop new observational projects that will bring us closer to a better understanding of these latest stages of the evolution of low-to-intermediate (∼0.8–8 M ) mass stars. Full article
(This article belongs to the Special Issue Workplans II: Workshop for Planetary Nebula Observations)
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Other

Open AccessConference Report
On the Age of Galactic Bulge CSPNe: Too Young and Complicated?
Galaxies 2020, 8(2), 51; https://doi.org/10.3390/galaxies8020051 - 18 Jun 2020
Abstract
We present preliminary results of our study of a small sample of planetary nebulae in the Galactic Bulge for which high-angular resolution Hubble Space Telescope imaging is available. From this and from archival spectroscopy, we were able to calculate temperatures and luminosities for [...] Read more.
We present preliminary results of our study of a small sample of planetary nebulae in the Galactic Bulge for which high-angular resolution Hubble Space Telescope imaging is available. From this and from archival spectroscopy, we were able to calculate temperatures and luminosities for their central stars. These were then correlated to up-to-date evolutionary tracks found in the literature to help us estimate stellar masses and therefore ages for the central stars. Our current analysis indicates that our sample appears to represent a somewhat mixed population of planetary nebulae central stars, while at least one of the nebulae might have been formed by a more massive progenitor (i.e., M ZAMS 4 M ). Full article
(This article belongs to the Special Issue Workplans II: Workshop for Planetary Nebula Observations)
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